But the shout-out to "lions of the Ummah" overnight in the Islamic State magazine Rumiyah, calling for attacks in "Brunswick, Broadmeadows, Bankstown and Bondi" is by far the best informed and most specific.

In the context of attacks on Paris and Nice, this makes it the most terrifying.

In Broadmeadows and Bankstown the anonymous author of the article has identified suburbs in Melbourne and Sydney where many Muslims live, and where there are active cells of radicalised Islamic State sympathisers.

Bondi, by contrast, is Australia's most famous hotbed of hedonism, and Brunswick a peaceful, mixed multicultural hub.

Was it the alliteration that attracted the authors to those suburbs, or the symbolism?

Probably both. The power of Islamic State's propaganda is that it is both intelligent and poetic; it fires the angst of young radical men at the same time as directing it.

"Light the ground beneath them aflame and scorch them with terror," the propagandist writes.

The presence of the Sydney Cricket Ground and Melbourne Cricket Ground in the list needs no explanation.

In finals season particularly, they are where hundreds of thousands of Australians gather and where, as the Bastille Day revellers in Nice found, they are vulnerable to a low-tech, brutal attack.

It demonstrates that whoever wrote this article has a detailed knowledge of Australia, and may be Australian.

And make no mistake: hundreds of people will hear the call.

An Australian journalist who went deep undercover with Islamic State's adherents in Sydney and Melbourne, says the magazine was republished overnight by the slick Islamic State media team to all supporters on their distribution lists.

He found it using the encrypted messaging application Telegram.

Sympathisers – some of whom have been stopped by police from travelling to Syria and Iraq, others who may not yet have come to police attention - were downloading it directly onto their mobile phones and reading it cover to cover.

Increasing its impact, the article was written to mourn the death in an air strike of a young Melbourne radical, Ezzit Raad.

Raad spent more than six years in jail in Victoria for his part in the Pendennis plot of 2005, which was led by Abdul Nacer Benbrika.

Raad died recently in the Syrian town of Manbij as he did the dirty work of Islamic State. In the words from their magazine, "a piece shrapnel struck him and tore his chest open".

Deakin University counter-terrorism expert Greg Barton said the message was "a reminder that we in Australia are high on their list".

"And there are hundreds, possibly thousands, who support them so it's also within reach."

In August 2014, Islamic State's propagandist-in-chief, Abu Mohammad al-Adnani, exhorted followers to carry out attacks at home.

What followed in Australia was the Lindt cafe siege, the attack on police by Numan Haider, the Anzac Day plot over which young Sevdet Besim was jailed this week, and the murder of Curtis Cheng by a 15-year-old gunman.

A similar threat was issued for Europe in May. Two months later, a "soldier of Islam" drove a 19-tonne truck through a crowd in Nice killing 86.

This latest threat should not make us change our behaviour, Barton insists.

But it will remind security forces that the threat remains a real, and very much a present, danger.